parathyroid gland

Question 1

what stimulates the release of PTH from chief cells

Answer 1

low blood calcium levels (hypocalcaemia)

Question 2

what stimulates parafollicular cells to release calcitonin

Answer 2

high calcium levels in the blood (hypercalcaemia)

Question 3

how does parathyroid hormone regulate calcium

Answer 3

binds to receptors on osteoblasts, stimulating then to release RANKL
RANKL receptor on osteoclast triggers the osteoclasts to become very active, breaks down chemicals within the bone
lots of calcium and phosphate accumulates, travels into the blood

Question 4

PTH effect on the kidneys

Answer 4

calcium is in the lumen of the filtrate waiting to go into the urine
calcium starts flowing from the filtrate into kidney cells and then into the blood

Question 5

PTH effects on cholecalciferol (CCF)

Answer 5

CCF goes to the liver and is converted to 25-hydroxycholecalciferol and goes to the kidney
PTH increases expression of 1-a-hydroxylase
they interact to form 1,25 dihydroxycholecalciferol (calcitriol - the active form of vitamin D)

Question 6

how does vitamins D increase calcium levels

Answer 6

acts on enterocytes in the duodenum
makes calcium channel proteins, calcium can enter enterocytes , increase in blood calcium levels

Question 7

how does calcitonin decease blood calcium

Answer 7

acts on receptors on osteoclasts, inhibits the osteoclasts